| Acton Precast Concrete Limited | Acton |
| A & B Precast Manufacturing Ltd. | Belleville |
Porters Infrastructure Products | Dresden |
| Brooklin Concrete Products Lindsay | Lindsay |
| Brooklin Concrete Products Huntsville | Huntsville |
| Boyd Brothers | Osgoode |
| Casselman Cement Ltd. | Casselman |
| Carson Supply | Port Elgin |
| J. A Porters Holdings (Lucknow) Ltd. | Lucknow |
| MacGregor Concrete Products Ltd. | Beachburg |
| Miller Precast | Thunder Bay |
| Moose Creek | |
| Newmarket Precast Concrete Products Ltd. | Uxbridge |
| Orangeville Precast Concrete Ltd. | Orangeville |
| Severn Bridge | |
| Planes Precast Concrete Ltd. | Kingston |
| Premier Precast Concrete Products | Trenton |
| Reid's Precast Cement Products Limited | Langton |
| Roswell Concrete Products Limited | Burford |
| Trevor's Concrete Shop | Porcupine |
| Underground Specialties | Oldcastle |
| Unit Precast (Breslau) Ltd. | Breslau |
| W.D. Moody Concrete Ltd. | Lowbanks |
| Wilkinson Heavy Precast Limited | Dundas |
| Winona Concrete and Pipe Products Ltd. | Grimsby |